Cooling system for internal-combustion engines



Oct. 1, 1946. J. CLAPSADLE' El'AL 2,408,374

cooune SYSTEM FOR INTERNAL-COMBUSTION ENGINES Filed Nov 11, ,1943

ENGINE BLOCK VENTURI l0 mvzu'rons 54 LEO J. CLAPSADLE JAMES c. KRATZER ERIC E SOMMER ATTORNEY with thelinain circulation line at ornear, the

point where lowest pressure in the system usually occurs. The latter point is normally in the vicinity of the propeller eye of the pump, but for con-,

venience, and to alleviate mechanical difficulties in making an attachment at this position; 'ajlowf pressure point can be created outside the pump by means of a Venturi tube or similar device,

Thus the liquid head pressure of the: coolant in the static tank and connecting leg is impressed on the system, which raises the pump pressure accordingly, and causes the minimum pressure.v

point in the system to be transferredto, and

remain in, the static tank. Suitable vaporfvent? ing means on the static tank aid in maintaining the pressure control indicated, and permitv an over-allpressurizing effect on the'system which is not substantially greater thanthat required toobtain continuouslya full circulation of coolant, With additional means for holding theteni-v perature of the coolant in the static tank higher than, it is in the pump, boiling will not-occur at,

or near, the pump; and pump cavitation and vapor binding. is prevented under all altitude con-. i ions- The accompanying drawing will be further' descriptive of the invention, and shows diagrammatically a cooling system embodimentwhich willproduce results as alleged.

In the drawing a primary circulating system is indicated for the engine block ill as including connective pipe l2, radiator- I4, connective pipe 16,; pump I8 and connective pipe 2i This primary circulating system according to our invention will also preferably include the Venturi tube 22, as shown just before thepump in connective pipe [6. The secondary; circulating system, through which. there isgonly a partial coolant circulation, includes connective pipe 24, leading from engine block In to an expansion tank 28,

and the return pipe 2'! connecting the expansion fioat'tfi Valve 34'will normally' be held in the;

closed position because of-the buoyant effect of the liquid in tank; 23, but will open to allow exit f;airgfrom tank 28 as entrained air is discharged andcollects at the top portion of this centrifuge tank. -Pipe 32, and associated parts, will readily permit flow of, air or vapor, but the needle valve 34 prevents substantial liquid flow between the tanks. I

- The pipe 33, with cap 40, providesa filler port ion-the system, and carries a bleeder pipe-42,-

which connects with the fioat chamber extension orrtank 28L This'bleeder pipe 42 is for the purpose of venting air during the initial filling, so that co mplete distribution of the coolant occurs throughout the system. The static coolant reserve tank tq is provided with a ven't pipe- 4.6,

4 which carries a safety valve 48, and leads to an outboard vent 50 through an adjustable diaphragm pressure release valve 52. The latter valve can be adjusted to control and hold a pressure which will prevent free boiling and excessive loss of vapor from tank 3 0,-and with, the aid of a""small orifice plate lgjust aheadlof the valve 52, venting of this valve can take place without allowing the system to equalize in pressure with the outside atmosphere.

'{A connection pipe 54 joins the static tank 30 to the throat of the Venturi 22, but since the system is completely closed and the main circulation .-line is entirely filled with coolant liquid,

there is very little, if any, coolant flow into the Venturi throat fromv the static tank. Thus the static liquid head pressure of the coolant in tank 30 and its'connectingleg is impressed at the point of lowest pressure in the system, and in accordance with the well-known hydraulic laws of Bernoulli, a corresponding pressure boost occurs in the pump, and'the pump intake pressure always exceeds the pressure in the static tank by an amount approximately that of the static liquid head at' the Venturi throat. The coolant in centrifugal tank 28, being taken directly from the engine block, keeps. the static tank coolant at a higher 'temp'erature'than the fluid entering the pump from the radiator, and this provides further assurance that boiling in the static tank will always occur before the coolant flowing to the pump reaches boiling' temperature. Hence a self-balancing pressurizing effect is attained, regardless of altitude conditions, and full pump circulation rate continues under all normal engine operating conditions.

It Will'be understood that many modifications over the systemspecifically described are possible, utilizing the essential features of the invention. As previously indicated a similar statictank assembly can be used without the Venturi-to produce good results,.in which case the connective leg of this t'ank is joined to the system directly at the pump intake, or at another position where minimum pressure exists. In place of;the Yen,- turi tube, anordinary orifice, Pitot tube, or similar device may be used to create a suitable low pressure zone before the pump. Maintenanceof asuitable temperature in the static tank liquid can be conveniently accomplished as shown, but a heat exchange arrangement withthe hot engine exhaust gases, or a surrounding;- rheostat-controlled electric heatenare other Waysof attaining the same end, and maybe equally suitable; With modified heating means for the static tank, the latter may be entirely separate from the expansion tank assembly, without a venting meansbetween the two tanks; in which case thereneed beno flow of fluid whatever through the static reserve tank. It is notessential that the. expansion tank be of centrifuge structure, as one of more conventional type may be satisfactory, where continual deaeration of the coolant-is not necessary or desired, and in thelatter situation the statictank itself might begmade to serve the additional. function of the usual expansion tank as areservoir for excess coolant; Many-embodiments' inthe way-of valves andventing means on both; the expansion tank and the static tank may also beappropriate to maintainthe required pressure control in;thesystem, and the relative positions and dimensions of the respective parts illustratedcan be varied to adapt the invention to,difierent engine assemblies.

The, above and other. modificationswill beob vious to those skilled in the art, and are intended to be included within the broader scope of the invention as defined in the appended claims.

We claim:

1. In a liquid cooling system for internal combustion engines having a primary circulation line including the engine block, a radiator and coolant pump, the combination of a coolant reservoir through which no substantial fluid flow occurs,

a connection from said reservoir to a point of normal low pressure in said primary circulation line, whereby head pressure of the reservoir coolant is impressed on the system, and means maintaining the temperature of said reservoir coolant higher than the temperature of the coolant in the circulation line at said connection point.

2. A system as defined in claim 1, in which the specified temperature of the reservoir coolant is maintained by heat exchange relation with hot effluent coolant from the engine block.

3. A system as defined in claim 1, in which the point of low pressure in the primary circulation line is created by a static pressure reducing device connected before the pump intake.

4. A system as defined in claim 1, which additionally includes a pressure venting means on said coolant reservoir adapted to control the vapor pressure therein.

5. A liquid cooling system for internal combustion engines comprising -a primary circulation line including the engine block, a radiator and a coolant pump; an expansion tank connected to permit at least partial circulation of eflluent engine block coolant; a static coolant reserve tank positioned in heat exchange relationship with the expansion tank coolant; a connection from said static tank to a point of normal minimum pressure in the primary circulation line, through which head pressure'o-f the static tank coolant'is impressed on the system; and pressure venting means on said static coolant reserve tank to control the vapor pressure therein.

6. A liquid cooling system for internal combustion engines comprising a primary circulation line including the engine block, a radiator and a coolant pump; an expansion tank connected to permit at least partial circulation of effluent engine block coolant; a static coolant reserve tank within said expansion tank and in heat exchange relationship with the coolant therein; a connection from said static tank to the pump intake, through which liquid head pressure of the static tank coolant is impressed on the system; and pressure venting means on said static coolant reserve tank to control the vapor pressure therein.

7. A liquid cooling system as defined in claim 6, in which said expansion tank is of a centrifuge structure adapted to deaerate the coolant circulating therethrough.

8. A liquid cooling system for internal combustion engines comprising a primary circulation line including the engine block, a radiator, a coolant pump, and a venturi before the intake to said pump; an expansion tank connected to permit at least partial circulation of eflluent engine block coolant; a static coolant reserve tank within said expansion tank and in heat exchange relationship with the coolant therein; a connection from said static tank to the throat of said venturi through which liquid head pressure of the static tank coolant is impressed on the system; and pressure venting means on said static coolant reserve tank to control the vapor pressure therein.

9..A liquid cooling system for internal combustion engines comprising a primary circulation line including the engine block, a radiator, a .coolant pump, and a venturi before the intake .to said pump; an expansion tank connected to permit at least partial circulation of efliuent engine block coolant; a static coolant reserve tank within said expansion tank and in heat exchange relationship with the coolant therein; a connection from said static tank to the throat of said venturi through which liquid head pressure of the static tank coolant is impressed on the system; a connection between said expansion tank and said static coolant reserve tank adapted readily to permi-t venting of air and vapor from the former to the latter tank and to resist similar flow of liquid; and pressure venting means on said static coolant reserve tank to control the vapor pressure therein while preventing an equalization of pressure with the outside atmosphere.

10. A liquid cooling system as defined in claim 9, in which said expansion tank is of a centrifuge structure adapted to deaerate the coolant circulating therethrough.

11. A liquid cooling system for internal combustion engines comprising a primary circulation line including the engine block, a radiator, a coolant pump, and a venturi before the intake to said pump; a centrifugal expansion tank connected to permit at least partial circulation of effluent engine block coolant; a static coolant reserve tank within said expansion tank and in heat exchange relationship with the coolant therein; a connection from said static tank to the throat of said venturi through which liquid head pressure of the static tank coolant is impressed'on the system; a connection between said expansion tank and said static coolant reserve tank adapted readily to permit venting of air and vapor from the former to the'latter tank and to resist similar flow of liquid, said'connecti'on including a valve operated by a float in said expansion tank; and pressure venting means on said static coolant reserve tank to control a vapor pressure preventing free boiling, while further preventing equalization of pressure with .the outside atmosphere.

' LEO J. CLAPSADLE.

JAMES C. KRATZER. ERIC E. SOMMER, 

